To prevent corrosion, buried pipelines and storage tanks (hereafter referred to as “pipelines”) are protected in two ways: by coating them with an insulating barrier that separates them from the corrosive effects of the soil; and, by making their surfaces cathodic with respect to their environment, a process called cathodic protection (CP). However, to ensure that the CP system is functioning properly and providing adequate protection to the pipelines based on minimum recommended standards, pipelines are regularly subjected to routine inspection called close interval potential surveys (CIPS). This is a rather time-consuming and labor intensive process because it involves traversing the entire length of the pipeline and taking pipe-to-soil potential (PSP) measurements at regular intervals of approximately three feet. This is made possible by a 2 to 3 mile of 34 gauge coated copper wire wound around a spool with one end connected to the pipeline, and the other to the positive end of a voltmeter.
Unfortunately, the copper wire is very fragile and often breaks along its length due to entanglements with obstacles, including the surveyor himself, along the right-of-way. The aspect of the wire breaks that is particularly of concern to this invention is at the spool-to-voltmeter end of the connection—a point where it is oftentimes too difficult or impractical to reconnect in the field. In this instance, most surveyors often discard the remaining length of wire spool, or drive a nail down the remaining spool to re-establish electrical connection, a method that is unreliable and still involves waste of the copper wire. It would be highly advantageous to have a means of maintaining electrical connection at this difficult location of the spool, thereby avoiding economic loss and excessive time waste during CIPS.
Examples of spooling apparatuses are shown in U.S. Pat. No. 4,151,458 (Seager) entitled “Closely spaced pipe-to-soil electrical survey method and apparatus” and U.S. Pat. No. 4,438,391 (Rog et al.) entitled “Electrical survey apparatus and method with spinner-type conductor supply”.